Where I did my PhD in ECE, we did not have a comprehensive written exam: we had to do research on a topic of interest to the student and the exam committee, write up a "conference paper" on the findings of the research, write up a separate paper on engineering research ethics, and give an oral presentation on the research topic. Questions from the qualifying exam committee during the presentation could cover both the research topic/findings and the engineering ethics paper written by the student.
To clarify, the research activities associated with the qualifying exam did not entail a formal research proposal: the formal research proposal at my previous department came at the preliminary exam stage. For the qualifier, researching a topic essentially meant different things to different students depending on how far along they were. For those students already working on a research project (which was/seemed to be a majority of students), the research write-up/presentation dealt with the findings up to that point and future directions (which naturally helped the student prepare for the prelim). For those students not fitting the above description, they would choose an area of interest to both the student and the committee (i.e., a research area where they see themselves working in the not-so-distant future with one or more faculty on the committee) and summarize the state-of-the-art, possible problems to tackle, along with some possible solutions/research directions.
What is the role that the qualifying exam fulfills in the PhD program in your department?
To ensure that the student:
- Is capable of doing independent research,
- Possesses the skills to present technical findings, both written and orally,
- Understands the ethical considerations that go into research/publishing, and
- Has a good command of the relevant technical material, from ECE graduate-level fundamentals to the state-of-the-art in the chosen topical area.
What are the perceived advantages / weaknesses of the approach?
I think the goals of the qualifying exam listed above were fairly-well addressed by the exam requirements. As for the downsides in the approach, some students were not yet capable of doing research at the level required by the exam. So I think our program weeded out some students who had the potential to do quality research but, unfortunately, were not "up to snuff" for their qualifier.